Method and device for generating 3d images

ABSTRACT

A method for generating three-dimensional images based on a sequence of two-dimensional images is characterized by the steps of: analyzing a two-dimensional image with respect to its scene type, selecting a deformation assigned to the defined scene type with which the two-dimensional image is deformed, deforming the two-dimensional image and transmitting the deformed two-dimensional image to at least one viewing channel. The method also contemplates applying various transition functions to the two-dimensional image to provide a continuous and smooth transition from one scene type to another. The method can be carried out by an apparatus for performing these functions.

This application is a continuation of U.S. patent application Ser. No.10/447,463, filed May 29, 2003, which is a continuation-in-part ofInternational Patent Application No. PCT/EP01/13674, filed Nov. 14,2001, both of which are hereby incorporated herein by reference in theirentirety. The International Patent Application has not been published inthe English language.

FIELD OF THE INVENTION

The invention relates to a method and a device for generatingthree-dimensional (3-D) images based on a sequence of two-dimensional(2-D) images.

BACKGROUND OF THE INVENTION

Scientists and medical professionals, for example, have analyzed objectsusing 3-D imaging for some time. But now various methods have beendeveloped to produce 3-D images, such as television images, for example,for general consumer applications. Among these methods, there is a basicdistinction between sequential image transmission, in which the imagesfor the right eye and the left eye are saved to a storage medium, ortransmitted alternately, one after the other, and parallel transmission,in which the images are transmitted on two separate channels.

One disadvantage of transmitting sequential images for displaying 3-Dimages in conventional television systems is that this reduces therefresh rate for each eye to 25 images per second, which creates anunpleasant flickering for the viewer. When transmitting the sequentialimages in parallel, on separate channels for the left and right eyes,the refresh rate is not reduced and thus flickering does not occur.Problems may still arise with synchronizing both channels, however.Problems also may arise due to the requirements of the receiver, whichmust be able to receive and process two separate channelssimultaneously. This is not possible for most television systems thatare now generally available to consumers.

In future television systems, signal transmission and processing willlikely be entirely digital. In a digital system, every image is brokendown into individual pixels which are transmitted in digitized format.In order to reduce the bandwidth required for this process, theappropriate compression methods are used; however, these create problemsfor stereo transmission. For example, using block coding methods with areasonable rate of compression, it is impossible to preciselyreconstruct every individual line of an image. In addition, usinginterframe coding techniques, such as MPEG-2, it is impossible totransmit or save stereo images in a sequential image format becauseimage information from one image is contained in another image. Thiscreates what is called the “crosstalk effect,” which makes it impossibleto clearly separate the right image from the left image.

Other methods with which a three-dimensional image sequence is generatedbased on a two-dimensional image sequence have been published in DE 3530 610 and EP 0 665 697. An autostereoscopic system with interpolationof images is described in EP 0 520 179, and problems with detectingareas of motion in image sequences are discussed in “Huang: ImageSequence Analysis” (Springer Publishing House).

U.S. Pat. No. 6,108,005 describes a method for generating syntheticstereo images in which at least two images are generated based on aloaded image. At least one of the generated images is adjusted(enlarged, reduced, rotated, displaced, or changed) relative to theloaded image in such a way that at least parts of the image aredisplaced relative to other parts of the image in comparison tocorresponding parts in another image. This method has the disadvantagethat it is largely dependent on the skill of the operator to select theproper adjustments to generate a correct or natural stereoscopicappearance for the viewer.

SUMMARY OF THE INVENTION

The present invention provides a method and an apparatus with which itis possible to generate 3-D images based on 2-D images, substantiallywithout intervention by an operator or viewer; moreover, theautomatically generated 3-D images have a particularly naturalthree-dimensional appearance.

The present invention provides an method and apparatus that enableson-the-fly or real time conversion of 2D images to 3D images withoutrequiring operator or viewer interventions, such as: selecting areas ofthe images, identifying objects in an image, selecting objects,outlining objects, displacing objects or segmenting images. By avoidingsuch image processing requirements, the method and apparatus provided bythe present invention eliminate the need for operator/viewerinterventions and yet also achieves real time performance.

More specifically, the present invention provides a method forgenerating three-dimensional (3-D) images based on a sequence oftwo-dimensional (2-D) images that includes the following steps:

analyzing a two-dimensional image with respect to its scene type;

assigning a deformation to the defined scene type;

deforming the two-dimensional image; and

transmitting the deformed two-dimensional image to at least one viewingchannel.

The method may further include the step of defining a scene type as oneof a close-up shot, a normal shot (medium shot), and a wide angle shot.

The step of assigning may include assigning a spherical deformation tothe close-up-shot scene type, in which case deforming includesdistorting the pixels of the two-dimensional image concentrically fromthe midpoint of the image outward.

Alternatively, the step of assigning may include assigning a sphere-tiltdeformation to the normal-shot scene type, in which case deformingincludes simultaneously distorting and expanding the pixels of thetwo-dimensional image from top to bottom and concentrically from themidpoint of the image.

As a further alternative, assigning may include assigning a tiltdeformation to the wide-angle-shot scene type, in which case deformingincludes incrementally, continuously, and horizontally expanding thepixels of the two-dimensional image.

The method also may include the step of producing first and secondviewing channels using different angles of observation of the deformedimage.

Further, the method may include the step of interpolating apredetermined number of sequential images from at least onetwo-dimensional image to produce at least a portion of the sequence oftwo-dimensional images.

When the scene type of an image is different than that of a previousimage, the method may include applying a transition function to theimage to continuously adjust the assigned deformation from thedeformation type assigned to the previous scene type to the deformationtype assigned to the new scene type to prevent an unnatural appearanceof the image. The step of applying the transition function may includeapplying a predetermined number of transition deformations and the newimage deformation, whereby the transition deformations are calculated byinterpolation of the previous deformation and of the new deformation forevery pixel.

The present invention also provides an apparatus for implementing themethod, characterized by a device for scene analysis of a loaded imageby defining at least a partial image and comparing the partial image tothe whole image.

Such a device for scene analysis may be equipped for defining a partialimage with variable size near the center of a whole image and forcalculating a root mean square deviation of the partial image and of thewhole image in order to define a scene type as a close-up shot or anormal shot based on this.

Such a device for scene analysis may be equipped for defining aplurality of partial images near the edge of the whole image and forcalculating an absolute amount of the cross-correlation betweendifferent areas of the image in order to define a scene type as a wideangle shot based on this.

The apparatus may further include an image deformation storage devicefor storing a plurality of scene types, one type of deformation assignedto each scene type, and one type of transition deformation assigned toeach transition between two deformations.

According to another embodiment of the invention, an apparatus forgenerating 3-D images includes an input to receive a sequence of 2-Dimages, a scene analysis device to analyze scene types of 2-D images, anumber of image deformation routines (matrices) related to respectivescene types, and an image deformation device for deforming 2-D imagesbased on scene type and associated deformation routine to providerespective sequences of 3-D images.

The apparatus also may include at least one of an image storage devicefor storing input 2-D images and a phase selector for providingrespective sequences of image for respective left eye and right eyeviewing as 3-D images.

The method described above also may be performed by a computer with anexecutable program and program code devices for performing the steps ofthe method. Such a program, as well as the program code devices, may bestored on a computer-data-readable medium.

The present invention also contemplates a digital image processingsystem for generating three-dimensional images that are transmitted orstored in two-dimensional format that includes the apparatus.

The claims fully describe and particularly point out the foregoing andother features of the invention. The following description and theannexed drawings set forth in detail an illustrative embodiment of theinvention; this embodiment is indicative, however, of but one of theways in which the principles of the invention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of circuitry according to theinvention;

FIG. 2 is a schematic representation describing a deformation by sphereprojection; and

FIG. 3 is a flow diagram of a method according to the invention.

The following description of an exemplary embodiment, with reference tothese drawings, provides additional details, features, and advantages ofthe invention.

DETAILED DESCRIPTION

The basic components of an apparatus according to the invention andtheir interconnections are schematically illustrated in FIG. 1. Theapparatus shown in FIG. 1 may be implemented in a digital imageprocessing system (not shown) for the generation of 3-D imagestransmitted or stored in a 2-D format. The apparatus generates the 3-Dimages from a series of 2-D images. The 2-D images may be recorded by acamera and digitized before they are provided to the apparatus providedby the invention.

Structure of the Illustrated Apparatus

The apparatus shown in FIG. 1 has a first input E for receiving the 2-Dimages, which are loaded into a first image storage device 1 for thetemporary storage of at least one of each given image.

The loaded images are transmitted from the first image storage device 1to a second image storage device 2, which is connected to the firststorage device 1 and is equipped to store and interpolate apredetermined number of sequential images.

In addition, a device 3 for scene analysis also is connected to thefirst image storage device 1. The current image stored in the firstimage storage device 1 is analyzed with respect to its contents by thedevice 3 in order to assign it to a specific scene type, such as“close-up,” “normal shot” (medium shot), or “wide angle shot.”

The device 3 for scene analysis is connected to a device 4 for imagedeformation, by which an image loaded from the first image storagedevice 1 is subjected to an image deformation assigned to this scenetype according to the scene type determined by the scene analysis device3.

The second image storage device 2 also is connected to the imagedeformation device 4. So, an image generated in the second image storagedevice 2 by interpolating previous images also can be deformed.

Different patterns for such image deformations and their assignment toat least one scene type are stored in an image deformation storagedevice 5, from which the patterns can be accessed by the device 4 forimage deformation.

In addition, a phase selector 6 is connected to an output of the imagedeformation device 4. Both the non-deformed image from the first imagestorage device 1, and the deformed image, which is based on thenon-deformed image, generated by the image deformation device 4, can betransmitted to the phase selector 6. The images are then connected to afirst or second output A1, A2 of the phase selector 6 and respectivelyform a first or second sequence of images, which are loaded to a left orright viewing channel BL, BR for a left or right stereo (3-D) image.

Thus, in the illustrated embodiment one image sequence is composed ofthe unaltered, loaded images and the other image sequence is composed ofthe deformed images that were generated based on the unaltered images(asymmetrical deformation). Alternatively, it is also possible to deformthe images of both image sequences (symmetrical deformation). Anadditional or alternative possibility is to load an image interpolatedin the second image storage device 2 into the image deformation device 4and to construct the first and/or second image sequence (deformed and/ornon-deformed) based on the interpolated image.

Interpolation of an image sequence x(i, j, α) stored in the second imagestorage device 2 is used to calculate the interpolated image; forexample, by linear spline approximation or a higher-level or polynomialapproximation of all pixels, where α is an approximation variablerepresenting the time interval from a given image during which asynthetic (interpolated) image is generated. International ApplicationPublication No. WO 01/76258 describes exemplary interpolation methods,which are incorporated by reference into this document.

Thus, with the apparatus provided by the invention, a first and a secondimage sequence can be generated based on a sequence of images that isrecorded in two dimensions and digitized. The digitized sequence of 2-Dimages is connected to input E, and the generated first and second imagesequence together make a 3-D view of the originally 2-D image possiblewhen the first and second image sequences are presented to a left orright eye.

Image Deformation Methods

In the following paragraphs, methods of generating the 3-D images aredescribed. First, a method for the generation of a stereo image sequenceby “asymmetrical” image deformation is described. In this method, theloaded image sequence, substantially unaltered (i.e., subjected to a“null deformation”), is used as the first image sequence and the secondimage sequence is generated by deformations of the images from the firstimage sequence.

Next, a second method for the generation of a stereo image sequence by“symmetrical” image deformation is described. In this method the imagesof the first image sequence are also deformed images.

Finally, it is then described how the type of image deformation can beselected and adjusted or optimized based on scene analysis in real timeaccording to image content (scene type) and how the transition betweendifferent image deformations can be made to avoid disruptive transitioneffects.

A.) Deformation Methods

Assume x_(ij) is a digitized image from the first image sequence at timet (first stereo image) with a horizontal resolution I and a verticalresolution J. The second stereo image x*(i*, j*) is derived as follows:i*:=i+i_index(i,j) or j*:=j+j_index(i,j).

This means that the new pixels i* and j* result from displacement in thedirection of i and j. In principle, any mathematical functions may beused for this; therefore, the deformations described below are onlyprovided as examples as such functions.

I.) Null Deformation Method

Three different deformations are illustrated for the first method:

1.) Tilt Deformation:

In this case, the pixels of the new image are expanded horizontally andcontinuously incrementally from top to bottom according to the followingformulas:i_index(i,j):=0;j_index(i,j):=(1−(tL−i)/tL)((0.5Ppl−j)/0.5PpL)*tiltfor i:=0, . . . , tL and j:=0, . . . , PpL

This means: tL is the number of lines, PpL is the number of pixels perline, and “tilt” is any scaling constant that defines the level ofexpansion.

2.) Sphere Deformation:

In this case, the pixels of the new image are distorted concentricallyfrom the midpoint of the image to its edge according to the followingformulas:i_index(i,j):=((0.5PpL−j)/0.5PpL)(1−(4/tL ²)(0.5tL−i)²)*spherej_index(i,j):=((0.5tL−i)/0.5tL)(1−(4/PpL ²)(0.5Ppl−j)²)*sphere

for i:=0, . . . , tL and j:=0, . . . , PpL

This means: tL is the number of lines, PpL is the number of pixels perline, and “sphere” is any scaling constant that defines the level ofdistortion.

3.) Sphere-Tilt Deformation:

In this case, the pixels of the new image are distorted and expandedsimultaneously from top to bottom and concentrically from the midpointaccording to the following formulas:i_index(i,j):=((0.5PpL−j)/0.5PpL)(1−(4/tL ²)(0.5tL−i)²)*spherej_index(i,j):=((0.5tL−i)/0.5tL)(1−(4/PpL²)(0.5Ppl−j)²)*sphere+((tL−i)/tL)((0.5PpL−j)/0.5PpL)*tilt

for i:=0, . . . , tL and j:=0, . . . , PpL

This means: tL is the number of lines, PpL is the number of pixels perline, “sphere” is any scaling constant that defines the level ofdistortion, and “tilt” is any scaling constant that defines the level ofexpansion.

II.) Symmetrical Deformation Method

The second method uses symmetrical image deformation, in which a givenoriginal image is deformed (e.g., geometrically distorted). In itsgeneralized form as shown in FIG. 2, it represents a picture of thegiven pixels 0 to PpL of an image plane B on a curved surface F (picturearea), whereby the picture is viewed at a distance D from twoperspectives for the left and right eye A1, A2. From the perspective ofthe viewer, the pixels (for example, z(j) or the area x_(M)) on thepicture area F are projected back onto the image plane B in differentmanners for each eye A1, A2 (j′ and x_(M)′ for A1 or j″ and x_(M)″ forA2). This creates the impression in the viewer's brain of viewing theimages from two angles of observation.

Again, in principle any mathematical functions or projection surfacescan be used. Examples of two deformations are described below:

1.) Sphere Projection:

In this case, the image area represents a convex spherical surface. Forevery original pixel x(i, j), a “synthetic” pixel z(i, j) will result ona spherical surface curved toward the viewer:z(i,j):=(1−(4/PpL ²)(0.5PpL−j)²)(1−(4/tL ²)(0.5tL−i)²)*sphere

Again, this means: tL is the number of lines, PpL is the number ofpixels per line, and “sphere” is any scaling constant which defines thelevel of distortion.

According to the theorem on intersecting lines, a j index is shown for aleft viewing position E₁ by:j′:={(j−E ₁)/(1−z(i,j)/D)}+E ₁

Since it is true that 0≦z(i, j)≦sphere, it may be seen that the “sphere”constant must always be smaller than the viewing distance D.

For the right viewing position E_(r), the following will result:j″:={(j−E _(r))/(1−z(i,j)/D)}+E _(r)

2.) Cylindrical Projection:

In this case, the image area represents a convex cylindrical surface.For every original pixel x(i, j), a “synthetic” pixel z(i, j) willresult on a cylindrical surface curved toward the viewer:z(i,j):=(1−(4/PpL ²)(0.5PpL−j)²)*sphere

Again, this means: PpL is the number of pixels per line and “sphere” isany scaling constant which defines the level of distortion.

For the new indices j′ and j″, the following will again result for aleft viewing position E₁, as with sphere projection E₁:j″:={(j−E ₁)/(1−z(i,j)/D)}+E ₁

and for a right viewing position E_(r):j″:={(j−E _(r))/(1−z(i,j)/D)}+E _(r)

The number of viewing positions is not limited to two for sphere orcylinder projection. Instead of just one left and one right viewingposition, basically as many left and right viewing positions E_(k) (k=1,. . . n) as desired can be calculated. This is particularly useful forautostereoscopic multi-viewer monitors.

Since values may not be assigned to all the indices of the new image bythe values j′ and j″ of both of the aforementioned indices, the “gaps”which arise because of this must be offset or “filled in” by subsequentsmoothing and interpolation processes.

For both methods (I and II), every individual deformation is preciselydescribed by the i_index and j_index indices. The values (displacementvalues) yielded by the above-stated formulas for the displacement ofeach pixel are stored in the image deformation storage device 5 for eachdeformation.

B.) Scene Analysis

Methods will now be described below with which scene analysis can beperformed and with which the type of image deformation used can bedynamically controlled or selected based on the scene type defined.

The method may use three different scene types for which the image willbe analyzed. In principle, however, a larger number of scene types canbe defined.

The examples of scene types described here are the close-up shot N, thewide angle shot, W, and the medium shot (normal shot) M.

In a close-up shot, an object is placed at the midpoint of the image andcovers the majority of the image from the midpoint outward. Sphereprojection is best-suited for deformation (conversion) in this case.This will also achieve a certain “pop-out” effect, in which the centerof the image appears to project out of the image toward the viewer.

Wide angle shots are often used for landscape shots. In this case, atilt deformation is generally used to achieve the best three-dimensionaleffect.

If there is a group of objects in the center of the image which is beingfollowed by the camera at a certain distance (normal or medium shot),the best three-dimensional effect is generally created by usingsphere-tilt deformation.

For the following calculations, P is first a fixed constant, whereP:=0.2 (0≦P≦0.5).

1.) Close-Up Scene Type

Defining the “close-up shot” scene type (N):

x_(N) is a rectangular partial image of a given image near the center ofthe image containing, for example, 60 percent of all the pixels in thewhole image x_(G).

δ_(G) ² is the root mean square deviation (variance) of the whole imagex_(G)=x(i, j) and, furthermore, δ_(N) ² is the root mean squaredeviation (variance) of the partial image x_(N). If δ_(N) ²≦Pδ_(G) ²,then the scene type has been defined as a close-up shot N. In this case,it will be true that:δ_(N) ²:=Σ(x _(ij) −x _(N))² over i, jεx_(N)

with the mean value x_(N):=(1/|x_(N)|)Σx_(ij) over i, jεx_(N).

2.) Medium-Shot Scene Type

Defining the “normal or medium shot” scene type (M):

x_(M) is a rectangular partial image of a given image near the center ofthe image containing, for example, 40 percent of all the pixels in thewhole image x_(G).

δ_(G) ² is the root mean square deviation (variance) of the whole imagex_(G)=x(i, j) and, furthermore, δ_(M) ² is the root mean squaredeviation (variance) of the partial image x_(M). If δ_(M) ²≦P δ_(G) ²,then the scene type has been defined as a medium shot M. In this case,it will be true that:δ_(M) ²:=Σ(x _(ij) −x _(M))² over i, jεx_(M)

with the mean value x_(M):=(1/|x_(M)|)Σx_(ij) over i, jεx_(M).

3.) Wide-Angle-Shot Scene Type

Defining the “wide angle shot” scene type (W):

x₁ and x₂ are two rectangular partial images in the left or right upperregion of the image, and y₁ and y₂ are two rectangular partial images inthe left or right lower region of the image. Furthermore, the absoluteamount of cross-correlation between the X regions of the image isdefined ask _(x):=|(Σx _(1i) x _(2i))/(√(Σx _(1i) ² Σx _(2i) ²))|

and the absolute amount of the cross-correlation between the Y regionsof the image is defined ask _(y):=|(Σy _(1i) y _(2i))/(√(Σy _(1i) ² Σy _(2i) ²))|

If it is true that k_(x)≧1−P and k_(y)≧1−P, then the X and the Y regionsare highly correlated. This is defined as the wide angle scene type W.

C.) Scene Transitions

When using image deformation, it must be remembered that when the scenetype is changed with respect to the previous scene type, it is not easyto switch between the assigned deformation functions. This would beperceived by the viewer as disruption or “slowing” or “jumping.”

In this case, a transition function distributes the previous deformationacross two or three images relatively smoothly or continuously carriesthe previous deformation over into a new deformation. Thus, thedeformation is dynamically adjusted to the new image content.

For this reason, a transition deformation is defined for everytransition from an “old” deformation to another “new” deformation, whichalso may be stored in the image deformation storage device 5. Such atransition deformation is formed of a preset number K of transitionmatrices. The values of the transition matrices also are stored in theimage deformation storage device 5, and are calculated by linearinterpolation of the displacement values, which are stored for eachpixel for the old and new deformations.

When the scene type changes, the transmitted image whose scene type haschanged is subjected to a transition function, which consists of thetransition deformation defined by the number K of transition matrices,and the subsequent new deformation assigned to the new scene type.

Any further scene changes, as determined by scene analysis are not takeninto account while the transition function is being applied. Forexample, assume that the scene type of the image which has just beentransmitted is “wide angle shot,” while the previously transmitted imagewas a “close-up shot.” Accordingly, one would switch from the (old)“sphere” image deformation assigned to close-up images to the (new)“tilt” image deformation assigned to wide angle shots. In addition,assume the number K=2, and two transition matrices are thus established.Therefore, before the new image deformation is used, the image which wasjust transmitted must be processed with the first transition matrix andthen the next image must be processed with the second transition matrix.These two matrices together form the transition deformation.

The individual values contained in the transition matrices and eachvalue representing the transition displacement of one pixel are derivedby linear interpolation of the displacement values of the old imagedeformation (sphere) and the new image deformation (tilt) according tothe number K of the transition matrices. For example, if thedisplacement value of the old image deformation is 0 and thedisplacement value of the new image deformation is 6.0 for a givenpixel, then for K=2 a displacement value of 2.0 will result for thispixel in the first transition matrix, and a displacement value of 4.0 inthe second transition matrix.

All transition matrices can be calculated in advance for all possibletransitions between scene types and thus between their respectivelyassigned transition matrices, and the matrices can be stored in theimage deformation storage device 5.

The transition matrices for transition from a first type of deformationto a second type will be applied to the transmitted image in reverseorder when there is a transition from the second type to the first typeof deformation.

Operation of the Illustrated Apparatus

FIG. 3 shows a flow diagram of a method according to the invention.

In the first step 10, after switching on the apparatus for imagedeformation 4, a first status, “Current deformation,” is set as thedeformation used for initial deformation, which may be cylinderdeformation, for example. In the second step 11, a second status, “Newdeformation” is set for a standard or default deformation, which mayalso be set to cylinder deformation, and then the scene type of thecurrent (loaded) image will be determined by means of the device 3 forscene analysis.

In the third step 12, a query is made to determine whether the scenetype defined is a close-up shot N. If so, the second status will be setto “New deformation:=sphere” in the fourth step 13, and it will continuewith (the ninth) step 18.

If the response to the query in the third step 12 is no, it will queryin the fifth step 14 whether the scene type defined is a medium shot M.If so, the second status will be set to “New deformation:=sphere−tilt”in the sixth step 15, and it will continue with (the ninth) step 18.

If the response to the query in the third step 14 is no, it will queryin the fifth step 16 whether the scene type defined is a wide angle shotM. If so, the second status will be set to “New deformation:=tilt” inthe eighth step 17, and it will continue with (the ninth) step 18.

If the response to the query in the seventh step 16 is also no, it willcontinue with the ninth step 18, which queries whether the types ofdeformation set in the first and second status are the same.

The steps 11 through 18 are performed with the device 3 for sceneanalysis.

If the response to the query in the ninth step 18 is yes, the currentimage will be subjected to (unaltered) image deformation by means of thedevice 4 for image deformation in the tenth step 19 and transmitted asan image in the second image sequence. The process is then repeated forthe next image starting with the second step 11.

If the response to the query in the ninth step 18 is no, the transitionfunction will be used, and the value k of a meter will then be set tok:=0 in the eleventh step 20.

Next, in the twelfth step 21 the current image of the image storagedevice 1 is deformed with the first transition matrix and transmitted asan image in the second image sequence. In addition, the value of themeter is increased by 1 (k:=k+1). In the thirteenth step 22, it willquery whether the meter count k is larger than the number K oftransition matrices.

If no, the twelfth step 21 will be repeated and the current image of theimage storage device 1 will be deformed by, of course, the second (next)transition matrix and then be transmitted as the next image in the(second) image sequence.

After the predetermined number K of transition matrices has been used,the now current image will be subjected to the new image deformationspecified in steps 13, 15, or 17 to complete the transition deformation,and the meter count will again be increased by a value of 1. Theresponse to the following query in the thirteenth step 22 will then beyes, so it will continue in the fourteenth step 23, during which thefirst status, “Current deformation” will be set to the new deformation.The process will then be repeated for the next image loaded by returningto the second step 11.

The methods described may be implemented in the form of one or morecomputer programs with program code devices for the performance of theindividual steps by a computer, in particular a microprocessor unit.

The methods can also be implemented as a computer program with programcode stored on a machine-readable medium for the performance of thesteps of the method if it is loaded into the memory of a programmablemicroprocessor unit or executed on a computer, whereby themicroprocessor or computer is a component of a digital image processingsystem.

Although the invention has been shown and described with respect to oneembodiment, equivalent alterations and modifications will occur toothers skilled in the art upon reading and understanding thisspecification and the annexed drawings. The functions performed by theabove described integers (components, assemblies, devices, compositions,etc.), and the terms (including a reference to a “means”) used todescribe such integers, are intended to correspond, unless otherwiseindicated, to any integer that performs the specified function of thedescribed integer (e.g., that is functionally equivalent), even thoughnot structurally equivalent to the disclosed structure that performs thefunction in the illustrated exemplary embodiment of the invention. Inaddition, while a particular feature of the invention may have beendescribed above with respect to only one of several possibleembodiments, such feature may be combined with one or more otherfeatures of the other embodiments, as may be desired and advantageousfor any given or particular application.

1-21. (canceled)
 22. A method for generating three-dimensional (3-D)images based on a sequence of two-dimensional (2-D) images, comprisingthe steps of: deforming a two-dimensional image based on its scene type;and transmitting the deformed two-dimensional image to at least oneviewing channel; wherein the deforming step includes defining asynthetic image such that a three-dimensional perception is created at aknown viewing position relative to the two-dimensional image.
 23. Amethod according to claim 22, comprising the steps of: analyzing thetwo-dimensional image to determine its scene type from a plurality ofscene types; assigning a deformation to each scene type.
 24. A methodaccording to claim 22, wherein the deforming step includes displacing atleast some of the pixels of the two-dimensional image from theiroriginal positions to define a synthetic image, defining a viewingposition at a known distance from a two-dimensional image plane, andgenerating a deformed two-dimensional image on the two-dimensional imageplane from the synthetic image.
 25. A method according to claim 22,comprising the step of defining multiple viewing positions andgenerating a deformed two-dimensional image for each viewing position.26. A method according to claim 22, wherein the deforming step includesdefining at least first and second viewing positions horizontally spacedfrom each other and generating first and second deformed images based onangles of observation from respective viewing positions; and thetransmitting step includes transmitting the first and second deformedimages to respective first and second viewing channels.
 27. A methodaccording to claim 22, further comprising defining a scene type as oneof a close-up shot, a normal shot, and a wide angle shot.
 28. A methodaccording to claim 22, wherein assigning includes assigning a sphericaldeformation to a close-up-shot scene type, and deforming includesdistorting the pixels of the two-dimensional image concentrically from apoint in the image.
 29. A method according to claim 28, whereindistorting includes forming the synthetic image with pixels z(i,j) fromthe two-dimensional image with pixels x(i,j) based on the followingformula:z(i,j):=(1−(4/PpL ²)(0.5PpL−j)²)*(1−(4/tL ²)*(0.5tL−i)²)*sphere where tLis the number of lines and PpL is the number of pixels per line, andsphere is a constant which is less than the distance from the imageplane to the viewing position.
 30. A method according to claim 22,wherein assigning includes assigning a sphere-tilt deformation to anormal-shot scene type, and displacing includes simultaneouslydistorting and expanding the pixels of the two-dimensional image fromtop to bottom and concentrically from a point in the image.
 31. A methodaccording to claim 22, wherein assigning includes assigning a tiltdeformation to a wide-angle-shot scene type, and displacing includesincrementally, continuously, and horizontally expanding the pixels ofthe two-dimensional image.
 32. A method according to claim 22,comprising interpolating a predetermined number of sequential imagesfrom at least one two-dimensional image sequence to produce at least aportion of the sequence of two-dimensional images.
 33. A methodaccording to claim 22, wherein when the scene type of an image isdifferent than that of a previous image, further comprising applying atransition function to the image to continuously adjust the assigneddeformation from the deformation type assigned to the previous scenetype to the deformation type assigned to the new scene type to preventan unnatural appearance of the image.
 34. A method according to claim33, wherein applying the transition function includes applying apredetermined number of transition deformations and the new imagedeformation, whereby the transition deformations are calculated byinterpolation of the previous deformation and of the new deformation forevery pixel.
 35. A system comprising a processor, a memory, an imageoutput, and program instructions for carrying out the method of claim22.